1. Field of the Invention
The present invention relates to a generally U-shaped unlocking lever which is vertically movable for causing unlocking operation of a lock mechanism associated with a seat slide device, wherein the seat slide device is adapted for allowing a seat to be adjustingly movable forwards and backwards via the upper and lower rails thereof. In particular, the invention is directed to a structure for supporting such generally U-shaped unlocking lever at the upper rail of the seat slide device.
2. Description of Prior Art
Various kinds of lock mechanisms are available for causing a seat slide device to be locked and unlocked at a given position. As well known, a pair of seat slide devices are operatively connected with a bottom side of a seat and operable for forward and backward adjustment of a seat. Each of the two seat slide devices comprises a lower rail fixed on a floor and an upper rail slidably fitted with the lower rail, wherein the upper rail is fixedly connected with a seat.
In most cases, a pair of lock mechanisms (known as a dual lock mechanism) are operatively attached to the foregoing pair of seat slide devices, respectively, to allow for stable locking and unlocking of the seat at a desired position. Hence, in order to cause synchronized and simultaneous operation of both two lock mechanisms of this kind, the Japanese Laid-Open Publication 2000-006694, for example, teaches use of a generally U-shaped unlocking lever which has a transverse handle portion for access to a seat occupant and a pair of lateral portions continuously extending from that transverse handle portion, wherein such pair of lateral portions are operatively connected with the afore-said two lock mechanisms, respectively. A seat occupant therefore can grasp the transverse handle portion with his or her hand and move the generally U-shaped unlocking lever in vertical direction to unlock both of the two lock mechanisms at the same time to release the seat slide device from a locked state.
In this sort of unlocking lever and dual lock mechanism, a pair of rotating holder brackets are normally provided to the respective afore-said two lateral portions of the generally U-shaped unlocking lever. In other words, those two lateral portions of the unlocking lever are rotatably connected, via such rotating holder brackets, with the two upper rails of seat slide devices, respectively.
In this regard, according to the foregoing Japanese prior art 2000-006694, a pair of support shafts are fixed to two upper rails associated with a pair of seat slide devices, and further a pair of rotating holder brackets are rotatably connected to the respective two support shafts, respectively. Such two rotating holder brackets are at their respective first ends firmly connected with the afore-said two lateral portions of the generally U-shaped unlocking lever, respectively, while being at their respective second ends operatively connected with the two lock mechanisms, respectively. Upward rotation of the unlocking lever causes downward rotation of the two second ends of that particular unlocking lever relative to the two support shafts via the two rotating holder brackets, thereby placing both two locking mechanisms in an unlocked state to release the seat slide device from locked state.
However, the above-described conventional structure has been with the following problems:
(i) If no coaxial alignment occurs between one and the other of the afore-said two support shafts due to errors in assembly, the generally U-shaped unlocking lever is not smoothly movable, and further, no synchronized operation of both two lock mechanisms can occur. To avoid such troubles, high precision and high expertise are required to locate and fix the two support shafts to the respective two upper rails associated with the two seat slide devices, which however will make the assembly of the lock mechanism and the unlocking lever in the seat slide device slower.
(ii) Since a great number of the generally U-shaped unlocking levers are provided for mass production processes, it is quite often the case that some of those levers are incorrectly formed with their respective lateral portions differing in angle and length from those of a required standard unlocking lever. In that case, since such incorrectly formed two lateral portions of the unlocking levers are fixed to the respective two rotating holder brackets, it is inevitable that the two rotating holder brackets will differ in angle from each other when they are fixedly connected with the respective two lateral portions of unlocking levers, which will result in no precise movement of the unlocking lever and no synchronized operation of the two lock mechanisms. Consequently, high precision and high expertise are required to form each unlocking lever correctly to a predetermined configuration. This will also make the assembling processes slower.